Thermal analysis, statistical predicting, and optimization of the flexural properties of natural fiber biocomposites using Box–Behnken experimental design

The object of this study is to investigate the flexural properties of biocomposites based on polypropylene/kenaf fiber/polypropylene-grafted maleic anhydride (PP/kenaf/PP-g-MA) using the response surface methodology. A three-factor, three-level Box–Behnken design, which is the subset of the response surface methodology, has been applied to present mathematical models as a function of kenaf fiber load, fiber length, and PP-g-MA compatibilizer content for the prediction of flexural strength and modulus behavior of the natural fiber biocomposite. Three levels were chosen for the considered parameters as follows: kenaf fiber (10–30 wt%), fiber length (2–10 mm), and PP-g-MA (1–5 wt%). Optimum compositions for better flexural properties were obtained from contour plots and response surface methodology. The results obtained using the design expert software showed the optimal flexural strength and modulus to be 53.66 and 3442 MPa, respectively. The obtained (Formula presented.) values and normal probability plots indicated a good agreement between the experimental results and those predicted by the model. Finally, the morphology and thermal stability of the samples were evaluated by scanning electron microscopy and thermogravimetric analysis.